A conventional supply pump includes a high-pressure pump that pressure-feeds high-pressure fuel, and a pump drive part which drives each high-pressure pump by rotation of an engine (see JP-A-2011-094596).
The pump drive part includes a cam that is rotated by the engine, and a driving force transfer mechanism that converts rotational movement of the cam to reciprocating movement in upper and lower directions (axial direction) to transmit the reciprocating movement to a plunger of the high-pressure pump.
The conventional technology has the following issues. The supply pump is provided not to cause a failure. Nevertheless, in case of any failure in the conventional supply pump, a tappet, which is provided for the driving force transfer mechanism, may excessively slide repeatedly in the upper and lower directions. If the tappet abnormally descends, a damage state of the supply pump may be made worse, for example, as a result of biting the cam by a part of the driving force transfer mechanism.